Improving bread aroma using low-temperature sourdough fermentation

To improve the aroma of bread, two aroma-producing yeast isolates from the Chinese liquor starter culture called Daqu, Meyerozyma guilliermondii CGMCC 17606 and Pichia kudriavzevii CGMCC 17607, were combined with Lactobacillus sanfranciscensis DSM20451T, were used for sourdough fermentation at 10, 20, and 30 °C. Volatile aroma compounds in bread crumb were extracted using headspace solid-phase micro-extraction and analyzed using gas chromatography-mass spectrometry and gas chromatography-olfactometry-mass spectrometry. The quality of the final bread was analyzed using sensory evaluation. Addition of sourdough fermented with mixed starters at 10 °C promoted bread aroma, showed increased sensorial qualities, and was preferred by panelists. Acetic acid, 1-octen-3-one, and dimethyl trisulfide, were the most aroma-active compounds in sourdough bread fermented with M. guilliermondii and L. sanfranciscensis, whereas those in sourdough bread fermented with P. kudriavzevii and L. sanfranciscensis were acetic acid, 1-octen-3-one, 2-methoxy-4-vinylphenol, 3-methylthio-propanal, furfural, and 1-(2-furanyl)-ethanone. Reducing the fermentation temperature to 10 °C increased the formation of these key volatiles, as well as other aroma-active compounds, such as 3-methyl-1-butanol, 3-methylbutanal, 2-methyl-1-propanol, 1-octen-3-ol, isogeraniol, benzaldehyde, benzene acetaldehyde, ethyl octanoate, ethyl decanoate, phenylethyl acetate, furfural, and 2-pentylfurane. The amount of furans, pyrazines, and volatiles converted from amino acids in bread crumb also increased with the protein hydrolyzation and amino acid formation in sourdough fermented at 10 °C. [Display omitted]